Swivel tube connection



J 1931- G. D. HOFFMAN I SWIVEL TUBE CONNECTION Filed June 9, 1925 Patented June 23, 1931 UNITED STATES PATENT oFncE GEORGE D. HOFFMAN, OF PASADENA, CALIFORNIA, ASSIGNOR TO HOFFMAN SPECIALTY COMPANY, OF WATERBUBY, CONNECTICUT, A CORPORATION OF ILLINOIS SWIVEL TUBE CONNECTION Original application filed January 24, 1922, Serial No. 531,425. Divided and this application filed June 9, 1925. Serial No. 86,055.

This invention relates to means or structures by which to connect together tubes m a manner permitting relative swivel ng movement between them and at the same time enabling them to be made substantially leakage tight, at least to the extent required for the particular uses to which the tubes so coupled are put. The main object of the invention is indil cated in the foregoing statement. A more particular object and field of usefulness of the invention is in connection with valves for vradiators of steam heating systems provided to relieve the radiators of accumulated air and in such cases the swivel connection is provided between a fixed tube in the valve and a si hon tube which depends from such fixed tu e, within the radiator, and is provided to drain water from the valve back into so the radiator. With this use more particularly in mind, a particular object of the invention has been to avoid liability of either tube being distended and enlarged at the swivel joint and of the vacuum being broken at such joint.

The particular embodiment of the invention here illustrated has been designed with reference to such a valve, and it comprises matter originall disclosed and claimed in my ap lication or patent filed January 24, 1922, erial No. 531,425, entitled Relief valve, on which PatentcNo. 1,548,313 was granted August 4, 1925. This application is, therefore, a division of theone above speclfied. However, it is to be understood that I claim the present invention and divisional subject matter, not merely as a part of such a relief valve, but for any combination and use for which it is adapted.

In the drawing forming a part of this ap lication the single figure represents a reliel valve for radiators shown in section and having a si hon tube connected thereto according to the principles of the present invention. I

Since the valve itself does not form an art of the invention herein claimed, it is su iicient to say in respect thereto that the numeral 5 deslgnates the casing and 19. a nipple which is threaded into a radiator and has a passage to receive air, steam, and water; that 20 represents a tube contained in the nipple 19, and smaller than its bore, for returning to the radiator water entrapped in the valve; and that 21 represents a curved siphon tube which is adapted to hang down within the radiator and is swiveled to the tube 20. The combination of the tubes 20 and 21 and the joint or coupling between them constitutes the invention for which I claim protection herein, and will now describe.

The tubes 20 and 21 overlap at their adja cent ends in themanner of the sections of a telescope. Considered in respect to their overlappin relationship, the tube 20 is the inner mem er of the coupling or tube connection and the siphon tube 21 is the outer member or tube. The inner tube is provided with two shoulders or collars or ribs 30 and 31 surrounding the tube and having a space 32 between them. Said shoulders are located at a certain distance from the extremity of the tube 20, for a purpose which will presently appear, said extremity being designated 33 and forming what may be called a trunnion end. If desired, there may be more than two such shoulders, to secure in greater degree the effect due to them.

The outer tube 21 surrounds the ribs 30 and 31 and has a free bearing thereon. It is also formed with an indented zone 34 which forms an internal shoulder surrounding and bearing on the trunnion end 33. The extremity or rim 35 of the outer tube 21 is spun or drawn down, and thus turned or set inward toward and substantially into contact with the surface of the tube 20 beside the shoulder 30. Thus there are four or more zones of bearing between the inner and outer tubes. Such bearings fit closely enough to render the spaces between the shoulders 30 and 31, and also that between the shoulder 30 and the spun-down lip 35, capable of receiving and retaining water enough to act as a seal, effective to prevent the entrance of air into the siphon tube at its upper end and so breaking the siphonic action. At the same time the bearing is loose enou h to permit the siphon tube to turn freely about the tube 20 and to hang vertically downward while the valve to which it is attached is being screwed into a radiator.

The bearings formed between the .two

tubes at the zones 30, 31 and '34 make im possible the spreading open of the spun-down lip 35 by rou h handling and knocking about. A serious de ect in swivel joints as heretofore applied to siphon tubes in radiator valves, has been that, as a result of rough handling, the joint would open or spread so as to loosen the swivel joint so much that the siphonic action was greatly impaired.- With my improved joint this eflI'ect cannot occur. I have found that when the connected tubes have been subjected to abuse by rough handling, bending, twisting, etc., the tube 20 would be fractured before any sign of strain was apparent in the spun-over lip 35. In other words, there is ractically no liability of the siphonic action ing impaired by leakage of air at the joint as the result of rough handling and abuse. I attribute this result to the fact that the reactions of all bending stresses which tend to affect the joint or coupling is takenby the bearin s at 30 and 34, and possibly at 31 also, an that the spun-down 11p 35 is thereby relieved of all stresses tending to distort and open it.

The security against separation of the connected tubes, which follows such protection 'of the spun-over lip, is of advantage in other circumstances than the particular case in which the connected tubes are parts of a si hon.

at I-claim and desire to secure by Letters Patent is:

1; The combination of two tubes, one of which projects at its end within the end of the other, the inner tube having two external encircling collars or ribs spaced apart from each other and from the adjacent end of the tube with an open space between them adapt- 7 ed to admit the liquid passing through-the tubes, said end forming a trunnion, and-the outer tube having an internal shoulder surrounding and bearing on said trunnion, and being set inward at its extremity toward the inner tube beyond the shoulder most remote signature.

the enlargement more remote from the trunmon end.

3. The combination of a tube having its outer end formed as a trunnion and havin an encirclin shoulder back from said en combined with a second tube of which one end has a larger diameter than said shoulder, and is passed over the trunnion end and shoulder of the first named/cube and set inwardly to form a lock cooperating with the shoulder in preventing itsremoval, the second tube havin also an indented zone at the outer side of said shoulder which is offset inwardly so as to form a bearing surroundmg and engaging the trunnion end of the first named tube.

In testimony whereof I have afiixed my from said trunnion, the portion of the outer tube between said internal shoulder and extremity being formed to surround and bear freely on the outer circumferences of said collars.

2. A swivel tube connection comprising two tubes telescopically overlapped at their contiguous ends, the inner tube having a trunnion end and'two enlargements spaced from said trunnion end and from one another, and the outer tube having an internal shoulder bearing on said trunnion end, an enlarged bearing portion surrounding and fitting rotatably about the said enlargement with sufficient looseness to admit liquid from the tubes into the open space between said enlargements, and an inwardly oifset zone outside of 

